Response of transpiration to rain pulses for two tree species in a semiarid plantation

Wei

Chen

et al. 2017

Ecological Engineering

a b s t r a c tTerracing has long been considered one of the most effective measures for soil water conservation and site improvement. However, few studies regarding the quantitative effects of terracing on soil water dynamics and vegetation water use efficiency were reported. To fill these knowledge gaps, in this study, soil water content and canopy transpiration from 2014 to 2015 were monitored in both terrace and slope environments in the semiarid Loess Plateau of China. Results showed that terracing had positive influences on soil water content among layers. Mean soil water content of the terrace site was 25.4% and 13.7% higher than that in the slope site in 2014 and 2015, and canopy transpiration at the terrace site increased by 9.1% and 4.8%, respectively. Canopy conductance at the terrace site was 3.9% higher than that at the slope site and it decreased logarithmically with the increase of vapor pressure deficit. This study highlighted the critical role of terracing in soil-water improvement and water-stress mitigation in semiarid environments. Thus, terracing has the potential to enhance sustainable vegetation restoration in water-limited regions.

Section: Implications Of This Studysupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Effects of terracing on soil water and canopy transpiration of Pinus tabulaeformis in the Loess Plateau of China

Wei

Chen

et al. 2017

Ecological Engineering

“…This assumption is supported by our observation that (i) 90% of the fine roots were within the upper 50 cm of the soil; (ii) the rooting density at soil depths >50 cm was very low (1 to 2 fine roots per dm 2 ); and (iii) soil moisture changes at the soil depths of 80 and 100 cm were less than 3 vol % during the balanced period. Similar soil water depletion patterns of black locust were observed by other studies [30,40]. Chen et al [30] measured soil moisture of black locust at the depth of 0-25 and 75-100 cm.…”

Section: Diurnal Cycle Of Transpiration Estimated Using Granier's Orisupporting

confidence: 72%

“…Similar soil water depletion patterns of black locust were observed by other studies [30,40]. Chen et al [30] measured soil moisture of black locust at the depth of 0-25 and 75-100 cm. They found insignificant soil moisture variations in the deeper soil during the vegetation season.…”

Section: Diurnal Cycle Of Transpiration Estimated Using Granier's Orisupporting

confidence: 72%

Improved Water Consumption Estimates of Black Locust Plantations in China’s Loess Plateau

Schwärzel

Strecker

et al. 2018

Forests

Black locust (Robinia pseudoacacia L.) is a major tree species in China's large-scale afforestation. Despite its significance, black locust is underrepresented in sap flow literature; moreover, the published water consumption data might be biased. We applied two field methods to estimate water consumption of black locust during the growing seasons in 2012 and 2013. The application of Granier's original sap flow method produced a very low transpiration rate (0.08 mm d −1 ) while the soil water balance method yielded a much higher rate (1.4 mm d −1 ). A dye experiment to determine the active sapwood area showed that only the outermost annual ring is responsible for conducting water, which was not considered in many previous studies. Moreover, an in situ calibration experiment was conducted to improve the reliability of Granier's method. Validation showed a good agreement in estimates of the transpiration rate between the different methods. It is known from many studies that black locust plantations contribute to the significant decline of discharge in the Yellow River basin. Our estimate of tree transpiration at stand scale confirms these results. This study provides a basis for and advances the argument for the development of more sustainable forest management strategies, which better balance forest-related ecosystem services such as soil conservation and water supply.

“…In China, there has been an increasing research focus on the sap flow characteristics in arid and semi-arid regions, where soil water is limited [39][40][41][42]. Many people think that water shortage problems only exist in arid or semi-arid regions.…”

Section: Discussionmentioning

confidence: 99%

The Relationship between Sap Flow Density and Environmental Factors in the Yangtze River Delta Region of China

Liu

Zhuang

et al. 2017

Forests

Abstract:Canopy transpiration is an important component of evapotranspiration, integrating physical and biological processes within the water and energy cycles of forests. Quercus acutissima and Cunninghamia lanceolata are two important, fast-growing and commercial tree species that have been extensively used for vegetation restoration, water conservation and building artificial forests in the Yangtze River Delta region of China. The primary objective of this study was to characterize sap flow densities of the two species by comparing daytime and nocturnal sap flow patterns and their relationships with environmental factors. Sap flow densities (S d ) were measured between September 2012 and August 2013 using the commercially-available thermal dissipation probes. Hourly meteorological data were measured in an open field, located 200 m away from the study site, including photosynthetically-active radiation (P ar ), air temperature (T a ), relative air humidity (R h ), vapor pressure deficit (V pd ) and precipitation (P). Soil water content (S wc ) data were logged hourly in different layers at Q. acutissima and C. lanceolata forests. Results indicated that the mean S d in summer was higher than that in spring and autumn. Both the S d of Q. acutissima and C. lanceolata showed distinct diurnal patterns. Nocturnal sap flow densities (S dn ) were noticeable, and both species followed similar declining patterns during our study period. The daytime sap flow density (S dd ) was more sensitive to environmental factors than S dn . Sap flow density was significant linearly correlated with P ar , V pd and T a , and P ar and V pd explained the greatest amount of variation in daytime sap flow of Q. acutissima and C. lanceolata, respectively. Our study will enrich knowledge of plantation forest physical and biological processes and provide valuable information for plantation forest management in the Yangtze River Delta region of China.